Apparatus for forming fibrous sheets or paperboard



Nov. 22, 1949 J. D'A. CLARK EI'AL 2,439,079

OR FORMING FIBROUS SHEETS OR PAPERBOARD APPARATUS Filed April 18, 1946Patented Nov. 22, 1949 APPARATUS FOR FORMING FIBROUS SHEETS R PAPERBOARD.lames an. mark, River Forest, and Sidney 1).

Wells, Combined Locks, Wis

its

., assignors to The Institute of Paper tlhemistry, Appleton, Win, acorporation of Wisconsin Application April 18, 1946, Serial No. 663,160

8 Claims. ll

Our invention relates to improvements in methods and apparatus forforming fibrous sheets or paper board.

One object of the invention is to provide means and a method by whichair laid fibers may be distributed uniformly and formed into a feltedproduct in a manner comparable to that found in products made by theusual water-forming method.

Another object is to provide apparatus for forming a mat of uniformdensity by blowing fibrous material through a foraminous partition anddepositing the fiber loosely on a conveyor and thereafter compressingthe mat.

A further object is to provide apparatus for forming building board ofuniform consistency by depositing on a moving screen, by means ofpressure and suction, an air-borne mixture of fiber and fine particlesof a thermal-setting adhesive, to which heat and pressure aresubsequently applied. 7

Another object is to provide apparatus having a forming area of greatextent in comparison with the rate of deposition of the material.

An additional object is to provide an improved method of forming a matof evenly distributed dense material containing a thermal-settingadhesive.

A further object is to provide an improved method of forming suchmaterial by the employment of a very dilute and highly dispersedsuspension of the fibers in the stream of air.

An additional object is to provide a method of forming building boardcomprising fibrous material and an adhesive, which consists of applyingsuction to the screen on which said material is deposited and thereafterapplying heat and pressure.

Other objects and advantages will hereafter appear.

In the drawings Fig. 1 is an end elevation somewhat diagrammatic inform, of a machine for making the product.

Fig. 2 is a section on the line 2-2 of Fig. 1;

Figs. 3 and 4 show various details.

In the machine selected for illustrative purposes, the fibers and abinder in the form of a finely powdered thermoplastic material are blownthrough a perforated rotating drum from the inside, more or lessradially outwardly, to a concentrically arranged wire mesh screen whichis spaced from the drum and which constitutes part of an endless belt orconveyor of foraminous material on which the felted material oruniformly distributed bat is formed.

The machine has a suitable frame I 0 which supports a rotatable cylinderor perforated drum H, mounted on roller bearing l2. Said drum is drivenat one end by a hollow shaft l3, which is mounted in suitable bearing itat one side of the machine, the opposite end of said drum being open. Agear or pulley I6 is fixed to said hollow shaft to rotate said drum.

The fiber with or without an adhesive mixed with it, is blown through aconduit ll into the open end of the drum; by a suitable blower it havingan inlet pipe l8 communicating with a supply of fiber, or fiberdispersed in air and finely ground thermal-setting adhesives, andcommunicating also with an opening in the housing 20 by an additionalconduit 2 l, thus forming in part a closed circuit.

It has proved dificult to secure uniform dispersion of air-borne fibersso as to provide a uniform bat or sheet, but we overcome this difiicultyby causing the fibers to pass through a coarse screen spaced a shortdistance from the forming wire, said screen in this case consisting ofthe perforated periphery of the drum.

The forming wire may consist, forexample, of 40-60 steel wire screen 22supported by chains comprising roller 39, links 23, 2t and cross bars 25which permit use of a wide conveyor screen without undue sagging. Saidchains which form the endless conveyor pass over idle rollers 26 and adriving roller 21, the direction of rotation being indicated by thearrow and the direction of rotation of the drum being preferably thesame as that of said conveyor The drum has radial blades 25 attachedthereto which act as fan blades to blow the material against theconveyor screen when the drum is rotating. Said blades may be solid orperforated with the perforations so spaced that the air currents formedby the rotation of the drum aid in uniformly distributing the fibers inthe form of a bat or felt. The cylindrical portion of the conveyor formsa chamber within the housing 20, into which the air-borne fiber isdelivered, said chamber comprising the annular space between the drumand the cylindrical wire surface which surrounds it. The fibers whichare not caught by the wire screen are drawn out of the housing by theconveyor through the pipe 2| and again discharged into the drum, thusforming a closed circuit. The blower not only delivers the fibers to thedrum under a. slight pressure but creates a slight suction on the wiremesh conveyor.

Within the drum a fanning frame is mounted comprising spiders 30 fixedto a shaft 3| with a,

' being provided to prevent leakage.

plurality of scrapers 82 mounted to scrape the insideof the drum toprevent the fibers from pluggins the perforations. Said shaft may berotated by a pulley or gear 33 thereon. Said shaft is mounted at one endin the bearing I5, passing through the sleeve 13. It is mounted in asuitable bearing 34 at the other end within the air circulating systemand at the axis of rotation of the drum.

The movement of the conveyor carries the felted product or bat out ofthe housing on a tangential span of said conveyor, a flapper valve 35being provided at the exit to prevent the leakage of an excessive amountof air into the housing. The bat, indicated at 36, is passed over aheating roll 31, around part of the periphery, on which press rolls 38are mounted. Thus the thermo-plastic material reacts under the heat andpressure provided, resulting in a dense compact product which may beused as a building board or for other purposes, depending on the degreeof heat and pressure employed.

Said bat may also be delivered from the apparatus in the form of aproduct having low density, through suitable attachments to cut the sameinto conventional widths for building purposes, 1. e. 16" widths, or forother purposes. The fibrous material may also be placed between sheetsof asphalt coated paper and made into moisture proof packages, or matsfor use in building construction. The link roller chains and crossconnections are preferably designed so that they will pass around adriving sprocket and also will produce both flat and concavecylindrical'surfaces, without wrinkling of the wire. In other words, thewire sections should abut without overlapping.

Where it is not desired to use a thermo-setting adhesive because of theloss in bulk which necessarily accompanies such use when the bat isheated and compressed as a final step of the operation, an adhesive insolution may be sprayed onto the fibers as the mat is being formed. Anysuitable adhesive may be used, as for example, water soluble adhesivesor those in colloidal suspension. The liquid employed may be pumpedthrough the pipe 40 (Fig. 2), into the annular space 4| and associatedparts which comprise a stationary joint, mounted on the revolving sleeveor hollow shaft l3, suitable packing material 42 Said liquid is thenconveyed to the axial passages 43 in said hollow shaft to radial pipes44 and thence to pipes 45 having suitable atomizing nozzles 46 mountedthereon, such as shown in Fig. l, to distribute the adhesivecontinuously on the bat as it is being formed on the cylindrical surfacepresented by the screen.

The portion of the travelling screen between the lower left and pair ofidler wheels 26"28" is not subject to the sprays from the nozzles justmentioned and it is thus possible to form a thin layer of fibers on thewire at that point, so that said adhesive does not come in contact withthe screen when the latter reaches the cylindrical portion of theforming surface.

One feature of the method employed is that a very high rate of aircirculation may be used if desired, without requiring a very largevolume of air. Also the air stream charged with fibers may be verydilute, i. e. the fibers may be highly dispersed, and it is possible touse a forming area of considerable extent under the circumstances. Theuse of a closed air system for the fibers is also desirable, in that itis convenient to mingle with said fibers any material which it isdesired 4 to add, and the existence of a chamber between the fan and theforming surface is also desirable.

We are aware that various changes may be made in the form andarrangement of the parts comprising the equipment described, withoutdeparting from the spirit of the invention as defined in the appendedclaims.

We claim:

1. In combination, a perforated drum, an endless conveyor mounted totravel in part along the arc of a circle concentric with and outside ofand spaced from said drum, means for blowing fibrous material throughthe perforations in said drum onto said conveyor, said conveyorcomprising a screen and'channel members formed to guide the edges ofsaid screen along said are and in a closed loop tangential thereto.

2. In combination, a perforated drum, means for rotating the same, ahousing for said drum, an arc-shaped track in said housing concentricwith said drum but spaced therefrom, chains guided by said track, andwire mesh screen extending from one chain to the other, a conduitcommunicating with the interior of said drums at one end to blow fibrousmaterial through said perforations and onto said screen to form. a mat,and means for advancing said chain.

3. In combination, a perforated drum, means for rotating the same, ahousin for said drum, an arc-shaped track in said housing concentricwith said drum but spaced therefrom, chains guided by said track, andwire mesh screen extending from one chain to the other, a, conduitcommunicating with the interior of said drum at one end to blow fibrousmaterial through said perforations and onto said screen to form a mat,means for advancing said chain, said chain having a span extendingtangentially from said are, to feed the finished mat out of saidhousing.

4. In combination, a housing having a perforated rotatable drum therein,an arc-shaped track mounted in the side walls of said housing andcomprising an incomplete circle, an endless conveyor comprising chainsslidable in said track, cross pieces connecting said chains and a wiremesh screen mounted on said cross pieces, said track extendingtangentially outward through an opening in said housing, idle rollers onwhich said conveyor is mounted outside of said housing, a conduitcommunicating with one end of said drum and a blower for deliveringfiber and finely ground thermo-setting adhesive to said perforated drumand onto said screen.

5. In combination, a housing having a perforated rotatable drum therein,an arc-shaped track mounted in the side walls of said housing andcomprising an incomplete circle, an endless conveyor comprising chainsslidable in said track, cross pieces connecting said chains and a wiremesh screen mounted on said cross pieces, said track extendingtangentially outward through an opening in said housing, idle rollers onwhich said conveyor is mounted outside of said housing, a conduitcommunicating with one end of said drum, a blower for delivering fiberand finely ground thermo-setting adhesive to said perforated drum andonto said screen, and means for compressing the mat formed on saidconveyor.

6. In combination, a housing having a perfo rated rotatable drumtherein, an arc-shaped track mesh screen mounted on said cross pieces,said track extending tangentially outward through an opening in saidhousing, idle rollers on which said conveyor is mounted outside of saidhousing, a conduit communicating with one end of said drum, a blower fordelivering fiber and finely ground thermo-setting adhesive to saidperforated drum and onto said screen, and a conduit extending from thespace between said conveyor and the wall of said housing to said blowerto return loose fibers to said drum.

7. In combination, a housing having a perforated rotatable drum therein,an arc-shaped track mounted in the side walls of said housing andcomprising an incomplete circle, an endless conveyor comprising chainsslidable in said track, cross pieces connecting said chains and a wiremesh screen mounted on said-cross pieces, said track extendingtangentially outward through an opening in said housing, idle rollers onwhich said conveyor is mounted outside of said housing, a conduitcommunicating with one end of said drum, a blower for delivering fiberand finely ground thermo-setting adhesive to said periorated drum andonto said screen, a, heated roll adjacent the end of saidtangential'track over which the felted material passes to cause saidadhesive to harden, and pressure rolls around the periphery of saidheated roll.

8. In combination, a housing having a periorated rotatable drum therein,an arc-shaped track mounted in the sidewalls of said housing andcomprising an incomplete circle, an endless conveyor comprising chainsslidabie in said track, cross pieces connecting said chains and a wiremesh screen mounted on said cross pieces, said track extendingtangentially outward through an opening in said housing, idle rollers onwhich said conveyor ismounted outside of said housing, a conduitcommunicating with one end of said drum, a blower for delivering airwith highly dispersed fibers and finely ground thermo-setting adhesivetherein, and means outside of said housing for applying heat andpressure to the felted material to harden the same.

JAMES dA. CLARK. SIDNEY D. WELLS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

